Md. Rabiul Awal, A. K. M. Saiful Islam, Md. Moshiur Rahman
et al.
ABSTRACT Optimizing the stocking density in bottom clean aquaculture is essential for promoting fish growth, economic sustainability and enhancing the general well‐being of fish. Three stocking densities (low, medium and high) were tested in a bottom clean aquaculture system to evaluate the growth efficiency, nutritional values, blood parameters, and cost‐effectiveness of Mystus cavasius . Fish stocking rates in tanks were 666 (low density), 1000 (medium density) and 1330 fish/m 3 (high density) with an initial fish weight of 0.49 ± 0.19 g, 0.48 ± 0.18 g and 0.50 ± 0.20 g, respectively. The results suggested that the water quality assessment was within acceptable limits for fish growth. The study revealed significantly higher ( p < 0.05) final weight, weight gain, percentage weight gain, average daily weight gain, specific growth rate, survival rate and feed conversion ratio (FCR) in the low‐density treatment. However, the total fish yield and profit were significantly higher in the high‐density treatment compared to the medium‐density and low‐density treatments, resulting in a higher net profit. Nutrient values were similar across all treatments. The length–weight relationship analysis indicated a negative allometric growth ( b < 3) with no significant variation ( p > 0.05) among treatments. The blood glucose and haemoglobin levels ranged from 129.50 to 157.75 mg/dL and 8.40 to 8.80 g/dL, respectively, among treatments indicating optimum levels. This study suggests that the ideal density for M. cavasius in tank‐based bottom clean aquaculture is 1330 fish/m 3 . However, further research is necessary to investigate higher stocking densities for optimal production.
Angle-resolved photoemission spectroscopy (ARPES) directly probes the energy and momentum of electrons in quantum materials, but conventional setups capture only a small fraction of the full 2$π$ solid angle. This limitation is acute in laser-based ARPES, where the low photon energy restricts momentum space despite ultrahigh resolution. Here we present systematic studies of bias ARPES, where applying a sample bias expands the accessible momentum range and enables full 2$π$ solid angle collection in two dimension using our 6.994 eV laser source. An analytical conversion relation is established and validated to accurately map the detector angle to the emission angle and the electron momentum in two dimensions. A precise approach is developed to determine the sample work function which is critical in the angle-momentum conversion of the bias ARPES experiments. Energy and angular resolutions are preserved under biases up to 100 V, and minimizing beam size is shown to be crucial. The technique is effective both near normal and off-normal geometries, allowing flexible Brillouin zone access with lower biases. Bias ARPES thus elevates laser ARPES to a new level, extending momentum coverage while retaining high resolution, and is applicable across a broad photon-energy range.
The aquaculture industry relies heavily on fishmeal as the primary protein source in aquafeeds. However, the increasing demand and limited availability of wild fish resources have led to a significant increase in fishmeal prices, posing a major challenge for the industry. Microbially fermented animal, plant, and single-cell proteins have emerged as potential alternative protein sources that offer a balanced nutritional profile at a lower cost. This review provides a comprehensive overview of the recent advancements in the utilization of fermented feed ingredients in aquaculture. This article focuses on research progress made in understanding the effects of fermented ingridient on nutrient absorption, growth performance, immune response of intestinal epithelial tissue, maintenance of intestinal microbial barriers, and impact on water quality in aquaculture systems. The two main types of fermentation processes, solid-state and liquid fermentation, are discussed along with their advantages and challenges. Factors affecting the quality of fermented ingredients, such as the type of microorganisms used, fermentation conditions, and substrate composition, were also explored. This review proposes strategies to promote and implement the use of microbial fermented ingredients in aquaculture practices, with the aim of developing a sustainable and cost-effective solution for aquafeed. The adoption of fermented feed ingredients has the potential to enhance the sustainability and profitability of the aquaculture industry, while meeting the growing global demand for aquatic products.
Alexandre Macedo João, Dulce Freire, Humberto Rocha
et al.
This study analyses Portugal’s wheat productive capacity, exploring the reasons behind its recent steady decline despite achieving self-sufficiency in the 20th century. Using Multivariate Adaptive Regression Splines (MARS), which proved to be highly effective in the development of forecasting models, the research provides valuable insights for countries facing similar challenges in defining production strategies. By employing this approach, decision-makers can improve resource allocation, ensure food security, and foster a resilient agricultural sector. The findings highlight the importance of understanding wheat production dynamics within the European Union and aligning national strategies with the Union’s goals and policies. The analysis indicates that achieving self-sufficiency is possible, supported by productivity improvements and increased cultivation areas. However, realizing significant production growth demands the adoption of sustainable strategies. This research contributes to shaping informed agricultural policies, enhancing decision-making processes, and promoting a more sustainable and efficient food production system to meet future challenges.
In aquaculture, increasing dietary fat levels can help to spare expensive protein resources and reduce water pollution. In some fish species, such as herbivorous fish, limited tolerance to dietary fat has emerged as a key factor affecting aquaculture sustainability, although the underlying mechanisms remain poorly understood. To address this, we investigated changes in juvenile grass carp Ctenopharyngodon idella on growth, muscle metabolomics, and gut microbiota in response to dietary lipid levels. A total of 270 fish (33.28 ± 0.05 g) were randomly assigned to three groups (triplicate) and fed isonitrogenous diets (30 % protein) with graded lipid levels (5 % control, 7 % and 9 % high-fat) for 8 weeks. Relative to the control, growth was enhanced at 7 % lipids but was significantly reduced at 9 % lipids (P < 0.05). The visceral and mesenteric fat ratios were elevated at 7 % and 9 % lipids and were highest at 7 % lipids (P < 0.05). Myocyte diameters were smallest in the control and largest at 7 % lipids (P < 0.05). Muscle metabolomics were significantly altered, at 7 %, the primary enriched metabolic pathways were lysine biosynthesis and glycine metabolism, while at 9 %, they were purine metabolism and taste transduction. Increasing lipid levels reduced the number of operational taxonomic units number and α-diversity of the gut microbiota. Bacteroidota abundance and phytuberin levels were significantly positively correlated at 7 % lipids; similarly Nakamurella abundance and guanosine levels showed a significant positive correlation at 9 % lipids (P < 0.05). Unclassified_f_Rhodobacteraceae abundance and acetic acid levels were negatively correlated at 9 % lipids (P < 0.05). Overall, Grass carp responded differently to varying dietary lipid levels. A moderate lipid increase (7 %) improved growth and affected amino acid metabolism, while excessive lipid levels (9 %) inhibited growth and altered muscle energy balance and nerve conduction. These effects were partly correlated with changes in the gut microbiota.
Michelle Thériault, Aleasha David, Simone Samson
et al.
Abstract Male lobsters ( Homarus americanus ) harvested as ‘quarters’ (1.25 lbs/567 g) in two time periods (winter, N = 16, and summer, N = 25) of 2018 are examined. Indicators of quality data were collected for each lobster, including non‐invasive measures (shell hardness, carapace length, sex, live weight, colour, body shape, location, time of harvest) and invasive measures (blood protein [BRIX] level at time of harvest, cooked weight, meat content). Lobster BRIX levels are used as a proxy for actual meat content and as the key indicator of lobster quality. A regression model of the relationship between the natural logarithmic transformation of lobster BRIX levels (independent variable) and meat content yield as a percentage of shell‐on (uncooked) weight (dependent variable) is presented. The objective of this study is to evaluate alternative BRIX‐based decision rules for achieving desired meat content percentage yields for preparing shipments to global markets. The present study found that BRIX‐based grading rules can be determined to achieve minimum desired meat yields, minimum overall shipment yields and minimum proportions of shipments below desirable yield rate. For a minimum desired industry threshold of 24% meat content, the preferred BRIX value rules are (i) 8.5 mg mL −1 and (ii) ‘9 mg mL −1 with 10% plus condition’. These rules improve the admissibility of samples and reduce the risk of below desirable meat yields.
Laban Musinguzi, Nathan Vranken, Vianny Natugonza
et al.
Abstract Poor and unreliable knowledge of the status of freshwater fisheries limits their inclusion in governance processes, thereby impeding effective management measures. This threatens the livelihoods of people, particularly in developing countries. Improved knowledge is required to draw the attention of policymakers and stimulate effective management measures to accelerate the sustainability of the freshwater fisheries. In line with this requirement, this paper provides the state of knowledge of the aquatic ecosystem and fisheries of the Lake Edward system, East Africa, focusing on lakes Edward, George and the Kazinga channel. The state of knowledge was accomplished by reviewing existing data and information on aspects of primary productivity and water quality, invertebrates, fish fauna, fish life history and ecology, and fisheries. The waterbodies have been monitored since the 1930s, albeit sporadically, providing data on all the above aspects but with substantial temporal gaps. Adequate and updated data and information exist on the water quality status of the water bodies, extant aquatic taxa (including fishes) and fish catches but with uncertainties in the latter. Data and information gaps exist on the abundance of biotic communities, fish life history, quantitative trophic ecology and fisheries management reference points. The aggregated data and information can directly support decisions for fisheries management. We recommend regular monitoring to fill the data and information gaps, more comprehensive stock assessments and the development of aquatic ecosystem models.
NK-lysin is a component of natural killer cells and cytotoxic T lymphocytes, and it plays an important role in the innate immune response of aquatic animals against various pathogens. In this study, a 640 base pair full-length cDNA sequence of the NK-lysin gene from black sea bass (Centropristis striata) (CsNKl) was obtained and analyzed. Tissue distribution results showed that CsNKl was widely distributed in various tissues of C. striata, but a significantly high expression level was detected in the spleen. CsNKl also exhibited time-dependent expression in different tissues after challenge with Vibrio harveyi. Two antimicrobial peptides (CsNKl-26 and CsNKl-28) were predicted from CsNKl proteins, and they demonstrated bactericidal functions against a variety of bacteria. Scanning electron microscopy analysis revealed that CsNKl-26 and CsNKl-28 played their bactericidal roles using the classical alpha-helix antimicrobial peptide route. These results illustrate the immune functions of CsNKl against V. harveyi, and they can be applied to developing disease control methods for fish.
M. Islam, Tanjila Akter Nipa, Md. Sofiqul Islam
et al.
Loss and damage have become a vital contemporary issue in climate change studies and actions in developing countries. How-ever, studies are scant on this in the fisheries sector around the world. In Bangladesh, there is no study on the loss and damage in fisheries dependent communities. This study assesses economic and non-economic loss and damage to coastal shrimp farms due to cyclone Bulbul in Gabura Union of Shyamnagar Upazila, Satkhira district, using a mixed method approach. Results show that all shrimp farms’ dependent communities are affected by cyclone Bulbul to some extent. About 14%, 57%, and 29% of the farms were totally, heavily and moderately damaged due to farm inundation and dyke damage. The estimated mean loss and damage per shrimp farm was worth USD 4,633. Around 31% and 72% of the farms’ fencing nets and traps were lost, which was worth USD 333 per farm. There were also loss and damage to other resources such as houses, solar panels, livestock and agricultural crops where the estimated mean loss and damage per household was worth USD 3,170. This study reported that the rich shrimp farmers encountered proportionately more economic loss and damage than their poor counterparts. However, this does not mean that the poor suffered less. The current study found a range of non-economic loss and damage in different aspects of the shrimp farmers’ household members such as unbearable mental pain, deterioration of health, physical injuries, disabilities, etc. and access to services (e.g., inadequate food, lack of safe drinking water, lack of medical facilities, disruption of education sys-tems), social infrastructure (e.g., damage of roads and markets) and disturbance of cultural functions. The findings suggest that urgent short- and long-term actions may be taken to save the aquaculture farms and dependent livelihoods from economic and non-economic loss and damage to cyclones in future.
Aquaculture supplies more than 50% of the total fish consumed by the world population. It is considered by FAO authorities that it will be the main source of fishery products by 2030. These positive data are contradicted by the fact that aquaculture relies too much on fish oil and fish meal as essential ingredients for food, which exerts significant pressure on marine ecosystems. The present study was planned to look for alternative ingredients in aquafeeds and three different ingredients were evaluated for the first time in juveniles of rainbow trout: (1) House cricket, Acheta domesticus, meal (DI) as a quality protein source; (2) a mixture of four marine microalgae species (DM), as an important source of protein and lipids; (3) protein and lipid fraction recovered from cooking water from canned tuna manufacturing processes (DP&L); and (4) a mix of the three ingredients (DMIX). All the feeds assayed were compared with a commercial feed (DC). Results showed that the formulated alternative feeds had different effects on the growth of the fish. DI and DP&L have a similar growth performance to the control, while the fish fed with DM and the DMix have a slightly lower growth (p < 0.05). No significant differences were observed in terms of FCR (Feed Conversion Ratio) and PER (Protein Efficiency Ratio) (p < 0.05). Fish muscle composition did not show any differences in moisture, protein, lipids and carbohydrates content. Only a significant difference was detected in ash and in saturated fatty acid (SFA) content (p < 0.05). The hepatosomatic index (HSI) was significantly reduced in DI compared to that observed for the DC (p < 0.05), whereas the viscerosomatic index (VSI) was significantly higher in DM. The nutritional value of the rainbow trout muscle at the end of the study shows that DM fed fish showed the highest PUFA/SFA ratio and the lowest atherogenic index (AI), whereas DMIX showed the lowest PUFA/SFA and the highest n-3/n-6 and AI. No differences were observed among diets in the thrombogenic index (TI) values. Any of these ingredients might be used as alternative sources of protein in feeds for fish aquaculture because no negative effects were detected on fish growth, muscle composition, fish health or final nutritional value, except in the case of microalgae, which needs more research to adjust its inclusion rate in the feed.
I Nyoman Giri Putra, Elok Faiqoh, I Gusti Ngurah Made Wiratama
The high demand for fish for local consumption and export has led to overfishing and increased the trade of fish that are prohibited by law and international agreements. Therefore, this study aims to calculate species diversity and determine the conservation status of fish traded in traditional fish markets in Bali. Field sampling was carried out at fish markets located in Badung, Buleleng, Karangasem, and Jembrana. Samples are identified to the lowest taxa level that can be determined, based on morphological characters. Diversity parameters such as the Shannon diversity index (H), Simpson (Simp), Fisher Alpha, Species richness (S) and Pielou's evenness (J) were calculated using the Rstudio while the determination of conservation status refers to the IUCN Red List. The number of fish samples collected was 69 individuals from 23 families. Of the total 69 individuals, 61 individuals were successfully identified to species level, while the rest of it were identified to the genus level. The results showed that the family of Labridae/wrasses has the highest number of species (9 species) followed by Clupeidae and Scombridae (7 species each). The result of diversity indices showed that the Kedonganan fish market (Badung) has the highest diversity. Evaluation of the conservation status of traded fish showed that 80% of the traded fish species are still in LC (Least Concern) status, although one species identified as bigeye tuna, Thunnus obesus, is known to have VU (Vulnerable) status.
Tingginya permintaan ikan untuk konsumsi lokal maupun ekspor menyebabkan terjadinya overfishing dan meningkatkan perdagangan ikan-ikan yang dilarang oleh undang-undang maupun kesepakatan internasional. Oleh sebab itu, penelitian ini bertujuan untuk menghitung keanekaragaman jenis dan menentukan status konservasi ikan yang diperdagangkan di pasar ikan tradisional di Bali. Pengambilan sampel dilakukan di pasar ikan yang terletak di kabupaten Badung, Buleleng, Karangasem, dan Jembrana. Sampel diidentifikasi sampai pada level taksa terendah yang bisa ditentukan, berdasarkan pada karakter morfologi. Parameter keanekaragaman seperti indeks keanekaragaman Shannon (H), Simpson (Simp), Fisher Alpha, Species richness (S) dan Pielou’s evenness (J) dihitung dengan Rstudio sedangkan penentuan status konservasi mengacu pada IUCN RedList. Jumlah sampel ikan yang dikumpulkan sebanyak 69 individu dari 23 famili. Dari total 69 individu, 61 individu berhasil diidentifikasi sampai pada level spesies sedangkan sisanya sampai level genus. Hasil penelitian menunjukkan bahwa Famili Labridae/wrasses memiliki jumlah spesies terbanyak (9 spesies) disusul oleh Clupeidae dan Scombridae (masing-masing 7 spesies). Hasil analisis keanekaragaman menunjukkan bahwa pasar ikan Kedonganan (Badung) memiliki keanekaragaman tertinggi. Evaluasi terhadap status konservasi ikan yang diperdagangkan menunjukkan bahwa 80% jenis ikan yang diperdagangkan masih dalam status LC (Least Concern) meskipun ditemukan juga satu spesies yaitu tuna mata besar, Thunnus obesus yang diketahui dalam status VU (Vulnerable).
Steven D. Rawles, Adam Fuller, Bartholomew W. Green
et al.
White bass (Morone chrysops) is a popular sportfish throughout the southern United States, and one parent of the commercially successful hybrid striped bass (M. chrysops ♂ x M. saxatilis ♀; HSB). Commercial production of white bass does not currently exist in the U.S. due to a lack of information regarding nutritional requirements and cost-effective diets as well as high production costs. Currently, white bass are cultured using diets formulated for other carnivorous fish that contain a significant percentage of marine fish meal (FM). We evaluated growth, survival, and body composition of white bass fed diets in which FM was replaced by various protein ingredients including soybean meal (SBM), poultry by-product meal (PBM), a combination of SBM, canola meal, and soy protein concentrate, or a commercial protein blend (Pro-Cision™). Six isonitrogenous (40% protein), isolipidic (11%), and isocaloric (17.1 kJ/g) diets were formulated using nutrient availability data for most of the dietary ingredients. Fish (40.2 ± 1.83 g) were stocked into a flow-through (2 L/min) culture system (3 tanks/diet; 10 fish/tank) and fed the test diets twice daily (7 d/wk) to satiation for 60-d. Test diets that replaced FM with various percentages of SBM and PBM resulted in similar performance as fish fed the control diet containing 30% FM. Fish fed the all-plant diet or the diet in which the commercial blend replaced FM resulted in reduced growth performance. Diet performance rankings based on response measures along with differences in essential amino acids and feed intake provided some insight into differences in diet performance. White bass can be fed fish meal-free diets without significantly reducing growth; however, replacement of FM exclusively with plant protein or commercial protein blends may need further study to ensure sufficient intake and performance. Limiting amino acid balance will also need to be addressed in future FM replacement trials with white bass.
Miguel Angel Puerto, Samar Saber, José María Ortiz de Urbina
et al.
Skipjack is an important commercial species with a tropical distribution, although captures in the Mediterranean Sea have been recorded for decades. The western Mediterranean Sea, specifically the Balearic Sea, is a spawning area for several tuna species. We hypothesized that the western Mediterranean warming in the last few decades could lead to the expansion of skipjack tuna spawning areas from tropical areas to the Mediterranean Sea. We analysed 454 individuals (41.8-81 cm straight fork length) caught by sport fishing vessels in offshore trolling championships in Spanish Mediterranean waters during summer months from 2014 to 2019. Analysis of the gonadosomatic index and microscopic examination of the ovaries (n=192) showed that the skipjack is reproductively active in the western Mediterranean, particularly in the Balearic Sea. These results indicate that the skipjack has expanded its distribution and spawning area from tropical waters to the Mediterranean, probably owing to the gradual warming detected in the area in the last few decades. This new spawning activity in the area should be monitored in the near future to study the possible impact on other tuna species that share the distribution range and spawning area with skipjack tuna in the western Mediterranean.